🐛 ClusterClass: fix reconciliation of MD delete

[sbueringer]

What this PR does / why we need it:
Currently it is not possible to delete MachineDeployments via Cluster.spec.topology,
because the code in current state assumes that for an existing MachineDeployment there is still an entry in Cluster.spec.topology.workers.

This was introduced in #7231 and thus v1.2 and main is affected

Follow-up:

• Open an issue to add integration or e2e test coverage: Extend ClusterClass changes e2e test to cover MD deletion #7404

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

[sbueringer]

/assign @fabriziopandini @killianmuldoon

[sbueringer]

/cherry-pick release-1.2

[k8s-infra-cherrypick-robot]

@sbueringer: once the present PR merges, I will cherry-pick it on top of release-1.2 in a new PR and assign it to you.

In response to this:

/cherry-pick release-1.2

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[killianmuldoon]

Follow-up to have this covered in some e2e test, or maybe just an integration test would work.

[killianmuldoon]

Fix is working for me, it also fixes clusters in a bad state from an upgrade from v1.2.3. i.e.
-> Delete machineDeploymentTopology in v1.2.3
-> See error in logs and failed deletion
-> Update CAPI controller to this PR
-> Topology properly reconciled
-> Adding and removing new MD topologies works as expected after this recovery.

[killianmuldoon]

/lgtm

[sbueringer]

I'll open an issue to extend the clusterclass changes e2e test to delete the MD we have at the end and verify that it's gone. Should be a straight-forward change and shouldn't even take longer, given that we have to delete the whole Cluster anyway.

EDIT: Done: #7404

[fabriziopandini]

Thanks for the quick fix, IMO this is worth an extra patch release sometime beginning next week
/lgtm
/approve

[k8s-ci-robot]

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This pull-request has been approved by: fabriziopandini

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[k8s-infra-cherrypick-robot]

@sbueringer: #7403 failed to apply on top of branch "release-1.2":

Applying: ClusterClass: fix reconciliation of MD delete
Using index info to reconstruct a base tree...
M	internal/controllers/topology/cluster/current_state.go
M	internal/controllers/topology/cluster/current_state_test.go
Falling back to patching base and 3-way merge...
Auto-merging internal/controllers/topology/cluster/current_state_test.go
Auto-merging internal/controllers/topology/cluster/current_state.go
CONFLICT (content): Merge conflict in internal/controllers/topology/cluster/current_state.go
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0001 ClusterClass: fix reconciliation of MD delete
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".

In response to this:

/cherry-pick release-1.2

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[sbueringer]

I'll open a cherry-pick PR

[sbueringer]

Thx @killianmuldoon for the additional testing!!